C++ IO流：标准输入输出流的重载

一、代码

#include <iostream>
using namespace std;

class Date
{
public:
Date(int year, int month , int day) : m_year(year), m_month(month), m_day(day) { }

//
friend ostream& operator<<(ostream& os, Date& dt);

private:
int m_year, m_month, m_day;
};

//
ostream& operator<<(ostream& os, Date& dt)
{
os<<dt.m_year<<"-"<<dt.m_month<<"-"<<dt.m_day<<endl;
return os;
}

int main(int argc, char*argv[])
{
Date yesterday(2015, 4, 2), today(2015, 4, 3), tommorrow(2015, 4, 4);

cout<<yesterday<<today<<tommorrow;

return 0;
}
二、输出结果